Do exotic salmonids feed on native fauna after escaping from aquaculture cages in Tasmania, Australia?

• Published in: Canadian Journal of Fisheries and Aquatic Sciences
• Main Authors: Abrantes, KG, Lyle, JM, Nicholas, PD, Semmens, JM
• Format: Article in Journal/Newspaper
• Language: English
• Published: Natl Research Council Canada 2011
• Subjects: Agricultural and Veterinary Sciences; Fisheries Sciences; Aquatic Ecosystem Studies and Stock Assessment; Fulton; Atlantic salmon; Salmo salar
• Online Access: https://doi.org/10.1139/F2011-057; http://ecite.utas.edu.au/75676

Atlantic salmon, Salmo salar, and rainbow trout, Oncorhynchus mykiss, are farmed in Tasmania, Australia, wherefish sometimes escape into the natural environment. If escapees are able to survive and feed on native fauna, it is likely thatthey will have ecosystem impacts. Stomach content, body condition (muscle lipid content and Fulton K), stable isotope,and fatty acid analysis were used to determine if escaped salmonids feed on native fauna. Results indicate that, in general,escaped salmonids do not feed on native fauna. Salmonids loose condition after escaping, and escapee stomachs weremostly empty or contained non-nutritious material or feed pellets. Nevertheless, almost a quarter of rainbow trout stomachscontained native fauna. The majority of escapees had biochemical composition similar to caged animals, indicating thatthese fish had not switched to feed on local food sources. However, a small fraction of escapees conclusively showedchanges in biochemical parameters indicative of a shift to feeding on native fauna. Given the numbers and frequency of escapes,this can have an important impact on native species and on the ecology of Macquarie Harbour.